Walstromite Mineral Data

General Walstromite Information

Chemical Formula:

BaCa2Si3O9

Composition:

Molecular Weight = 445.73 gm

Barium 30.81 % Ba 34.40 % BaO

Calcium 17.98 % Ca 25.16 % CaO

Silicon 18.90 % Si 40.44 % SiO₂

Oxygen 32.31 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

BaCa₂Si₃O₉

Environment:

Metamorphosed metasediments.

IMA Status:

Approved IMA 1965

Locality:

Big Creek - Rush Creek sanbornite deposit, 5 miles NE of Trimmer, Fresno Co., California. Link to MinDat.org Location Data.

Name Origin:

Named for Robert E. Walstrom (1920-), American mineral collector, who discovered the mineral.

Name Pronunciation:

Walstromite + Pronunciation

Walstromite Image

Images:

Walstromite

Comments: Colorless massive walstromite with pronounced cleavage, showing strong orange-pink fluorescence under long-wave ultraviolet light in inset image.
Location: Esquire number 8 mine, Big Creek, Fresno County, California, USA. Scale: See Image.
© Rruff Database

Walstromite Crystallography

Axial Ratios:

a:b:c =0.6991:1:0.7001

Cell Dimensions:

a = 6.723, b = 9.616, c = 6.733, Z = 2; alpha = 83.1°, beta = 77.67°, gamma = 69.62° V = 395.73 Den(Calc)= 3.74

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.99(1), 2.7(0.2), 6.58(0.2),

Crystal Structure:

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Dent Glasser L S , Glasser F P , American Mineralogist , 53 (1968) p.9-13, The crystal structure of walstromite

Physical Properties of Walstromite

Cleavage:

{011} Perfect, {010} Perfect, {100} Very Good

Color:

Colorless, White.

Density:

3.67

Diaphaneity:

Transparent

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Hardness:

3.5 - Copper Penny

Luminescence:

Fluorescent, Short UV=pale pink, Long UV=pinkish orange.

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Walstromite

Gladstone-Dale:

CI meas= -0.022 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.009 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1825,KPDmeas= 0.185,KC= 0.181
Ncalc = 1.66 - 1.67

Optical Data:

Biaxial (-), a=1.668, b=1.684, g=1.685, bire=0.0170, 2V(Calc)=26, 2V(Meas)=30. Dispersion weak.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Walstromite

Electron Density:

Bulk Density (Electron Density)=3.51 gm/cc
note: Specific Gravity of Walstromite =3.72 gm/cc.

Fermion Index:

Fermion Index = 0.06
Boson Index = 0.94

Photoelectric:

PE_Walstromite= 134.15 barns/electron
U=PE_Walstromite x rElectron Density= 470.24 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Walstromite is Not Radioactive

Walstromite Classification

Dana Class:

59.01.02.01 (59)Cyclosilicate Three-Membered Rings

(59.01)anhydrous, no other anions

(59.01.02)Walstromite group

59.01.02.01 Walstromite BaCa2Si3O9 P1 1

59.01.02.02 Margarosanite Pb(Ca,Mn)2Si3O9 P1 1

Strunz Class:

09.CA.25 09 - SILICATES (Germanates)

09.C - Cyclosilicates

09.CA -[Si3O9]6- 3-membered single rings (dreier-Einfachringe),

09.CA.25 Margarosanite Pb(Ca,Mn)2Si3O9 P1 1

09.CA.25 Walstromite BaCa2Si3O9 P1 1

Other Walstromite Information

References:

NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Walstromite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Ask about Walstromite here :
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Print or Cut-and-Paste your Walstromite Specimen Label here :

Walstromite

BaCa2Si3O9
Dana No: 59.01.02.01 Strunz No: 09.CA.25
Locality:

Notes: